For the past thirteen years, the Transplantation Biology Unit at UCLA has been involved in a continuing program of bone marrow transplantation and alternative therapies in the treatment of patients with aplastic anemia, leukemia, cancer, and immunodeficiency diseases. Many of these patients have become long-term survivors but considerable problems remain to be addressed including prevention of graft rejection, graft-vs-host disease (GVHD), delay of immune reconstitution and interstitial pneumonia. This proposal outlines our ongoing studies in three major program areas: (1) clinical trials; (2) the immunobiology of bone marrow transplantation and (3) application of hematopoietic growth Factors for transplant recipients and for treatment of hematologic diseases. These studies include preclinical studies in dogs and controlled clinical trials in patients with hematologic malignancies and aplastic anemia. The objective of the proposed project is to determine the role of bone marrow transplantation in human disease and improve the results of its application by an in- depth analysis of basic problems of transplantation biology in animals and by appropriate clinical trials.